Rev. A. Irving — Triassic Deposits of the Alps. 499 



tation, in the Central Alps. It is only as we proceed eastward to 

 the longitude of the eastern part of Lake Constance that we find any- 

 great developraent of the series ; and this, progressing as we advance 

 tlirongh the Vorarlberg, would appear to reach its maximum in the 

 Salzburg country on the north side, and in the S. Tirol and West 

 Venetian Alps on the south side, of the principal crystalline axis. 

 The relations of these massive deposits, for the most part more 

 or less of the character of limestones (their greatest development 

 being either limestones, dolomitic limestones, or dolomites) to the 

 more central crystalline rocks, have determined some of the most 

 salient features of the orography of the Alps. Thus it is, broad!}'- 

 speaking, along the lines of strike of the Triassic strata that several of 

 the finest and longest longitudinal valleys have been formed. Examples 

 of this which at once occur to one are the Inn Thai (from Landeck 

 to Schwaz), the Pinzgau, and the Enns Thai to the north, and the 

 Puster Thai (the largest longitudinal vallej^ of the Alpine chain) to 

 the south of the crystalline axis. The splendid panorama presented 

 to the view from the top of the Schmittenhohe near Zell-am-See, 

 shows ver}^ well the difference between the general physiography of 

 the Triassic strata to the north, and the crystalline mountain masses 

 (as represented by the Glockner Group) to the south. In a similar 

 way the view from the top of the Eittner Horn enables us to make 

 a comparison between the scenery of the beautiful region of the 

 ' Dolomite Alps ' in one direction, and that of the glacier-regions of 

 the Ortler Group and the Oetz-Thal Group in the other. 



Lines of anticlinal curvature of the strata on a large scale (though 

 quite subordinated to the principal anticlinal of the whole chain) 

 may be distinctly observed in places. Such an anticlinal for example 

 is seen to extend through the upper part of the Grodner Thai by 

 Cortina in the Ampezzo Thai to Piave di Cadore. In this line of 

 valley two principal passes are crossed ; and since neither of these 

 is of sufficient elevation to be covered with glaciers, the structure 

 of the valley along the whole line is easily observed. Instances in 

 which there is such a clear connexion between the direction of a 

 valley and a line of weakness amounting to SiCixxdl fracture, along an 

 anticlinal axis, are perhaps not often to be met with. Of course in 

 this case the grass-grown floor of the valley, through the greater 

 part of the line, leaves the origination of the valley to be inferred 

 from the unmistakable dip in opposite directions, not only of the 

 massive limestone strata, but also of the more thinly stratified 

 Wenger Schichten and Bunter strata, which are seen in places dip- 

 ping into the mountain-side beneath the dolomitic masses, which 

 constitute the often grotesque elements of the scenery of the region ; 

 but on the passes the evidence is a matter of more direct observation. 

 This is especially so in the case of the Grodner Joch, at the head of 

 the Grodner Thai. The Pass itself is a rather sharp saddle, in the 

 lowest part of which the strata are clearly exposed to view on both 

 sides of the footpath, and the actual line of fracture of the beds is 

 visible. The accompanying sketch (Fig. 1) will make this more 

 clear (see p. 502). 



